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Anharmonic corrections to the multiphonon deep-level charge capture ab initio calculations for semiconductors

Nonradiative carrier recombination at semiconductor deep centers is of great importance to both fundamental physics and device engineering. In this letter, we provide a revised analysis of K. Huang's original nonradiative multi-phonon (NMP) theory with ab initio calculations. First, we identify at first-principle level that Huang's concise formula gives the same results as the matrix based formula, and Huang's high temperature formula provides an analytical expression for the coupling constant in Marcus theory. Secondly, the anharmonic effects are corrected by taking into account local phonon mode variation at different charge states of the defect. The corrected capture rates for defects in GaN and SiC agree well with experiments.